CN1303739C - Automatic master-slave parallel control method for sine pulse width modulation inverter power supply - Google Patents

Abstract

The present invention discloses an automatic master-slave parallel control method of an SPWM inverter power supply. The present invention adopts the instantaneous reactive power principle and the output power characteristics of a parallel inverter power supply, namely that the active power of the output is controlled by changing the frequency of the output voltage of the inverter, and the reactive power of the output is controlled by the amplitude value of the output voltage of the inverter. Consequently, decoupling control can be carried out to the frequency or the phase position and the amplitude value of the inverter power supply by the output active power P and the reactive power Q. An interconnection signal wire exists in a system, but the signals transmitted by the interconnection signal wire are all direct current which can conveniently inhibit the interference in the process of long distance transmission. Consequently, the automatic master-slave parallel control method has the advantages of superior use value, good flow equalization effect and high stability of the voltage frequency and the amplitude value of the system in a distributed generation system and a UPS system. In the distributed generation system and the UPS system, the automatic master-slave parallel control method of an SPWM inverter power supply of the present invention has favorable application prospects.

Description

The automatic host-slave parallel control method of sinusoidal pulse width modulation inverter

Technical field

The invention belongs to technical field of electricity, relate to the sinusoidal pulse width modulation inverter multi-machine parallel connection progress control method in the systems such as distributed generation system, UPS.

Background technology

The parallel running of many sinusoidal pulse width modulation inverters can enlarge the capacity of system, but also can form parallel redundant system to improve the reliability and the maintainability of system.But, the parallel running of sinusoidal pulse width modulation inverter is difficulty relatively, because frequency, phase place and the amplitude of the sinusoidal pulse width modulation inverter of all parallel runnings all must be consistent, otherwise, to there be very big circulation between each inverter, excessive circulation can make the burden of inverter, and the circulation of dispersing will make system crash, cause power failure.

The parallel Operation Control mode of sinusoidal pulse width modulation inverter generally is divided into centralized control, principal and subordinate's control and does not have interconnected holding wire independence controlling schemes.Existing centralized control need detect total load current, and by the holding wire of higher bandwidth the information of load current is passed to all inverter modules, and this has had a strong impact on the dilatation of system; There is interconnective holding wire in the system, makes the reliability of system reduce; System is not redundant, could realize parallel running under the control of current distribution unit, in case current distribution unit is damaged, system will collapse.

Compare with centralized control, principal and subordinate's control mode has certain advantage, and it can not need detect the size of load current, and the system that makes is easy to the expansion capacity; And the control between inverter is not subjected to the influence of inverter outlet line impedance, and the current-sharing effect of system is fine.But principal and subordinate's control mode also has some shortcomings: the existence of primary module makes that it is not a redundant system, in case primary module breaks down, whole system will be paralysed; The stability of a system depends in parallel from number of modules; Primary module and from there being the current command signal line between the module should not be grown distance and lay, otherwise signal can big high attenuation, serious interference, phase place seriously lag behind.

Compare with preceding two kinds of Parallel Control modes, do not have interconnected holding wire independence control mode and do not need interconnected control signal wire, the sagging control of frequency, amplitude by output voltage realizes dividing equally of load active power and reactive power, thereby realizes dividing equally of load current.This mode is particularly useful for distributed generation system, but, reactive power to divide equally the influence that is subjected to line impedance comparatively serious, if the line impedance coupling is bad, then the required reactive power of load will can not get fine dividing equally, so this mode requires very high to system's detection, control precision; And this mode is owing to adopt droop characteristic, electric voltage frequency, the amplitude stability index of the output of meeting sacrificial system.

Summary of the invention

Because centralized control, principal and subordinate's control belong to the nonredundancy structure, will cause the whole system collapse when the master-slave unit fault, system reliability is poor; And exist a large amount of control signal wires to transmit the control signal that becomes when exchanging, signal is decay and serious interference in the process of long Distance Transmission; Simultaneously, the existence of control signal wire also is unfavorable for the laying of supply line, the cost height of system.Centralized control needs the load current of detection system, and in distributed generation system, load distributes too, and the detection of load current is difficult to.Therefore, in distributed generation system, general employing centralized control and the principal and subordinate's control mode of being difficult for.

The objective of the invention is to, a kind of automatic host-slave parallel control method of sinusoidal pulse width modulation inverter is provided, this method is the improvement of the host-slave parallel operation control method of offset of sinusoidal pulse-width modulation inverter.

The solution that realizes the foregoing invention purpose is: a kind of automatic host-slave parallel control method of sinusoidal pulse width modulation inverter is characterized in that this method may further comprise the steps at least:

With meritorious primary module and the idle primary module in the automatic principal and subordinate's control system of inverter, by selecting the control of master unit automatically, automatically the big module of active power of output as meritorious primary module, all the other modules then for meritorious from module, active power bus P _BUSValue by the active power of output decision of meritorious primary module; By selecting the control of master unit automatically, exporting the big module of reactive power as idle primary module, all the other modules then are idle from module, reactive power bus Q automatically _BUSValue by the reactive power decision of idle primary module output, all desirable reactive powers from module output all should be Q _BUSValue;

Every inverter is from electric current I and the output voltage V of module by sampling oneself output ₀Calculate the active power P of output _iAnd reactive power Q _i, and respectively with active power bus P _BUSWith reactive power bus Q _BUSRelatively, obtain active power deviation and reactive power deviation, again with the active power deviation as phase place  _iCompensation rate, reactive power deviation are as amplitude U _iCompensation rate is adjusted the voltage of output, realizes each inverter load-sharing power in parallel and the sharing control between inverter;

If the capacity of inverter in parallel does not wait in the system, then the active power and the reactive power of its output are handled according to following mark change relational expression according to the capacity of inverter:

$\frac{P_1}{{\mathrm{<figure-callout\; id="1"\; label="S"\; filenames="C0310804700162.png,C0310804700173.png"\; state="\{\{state\}\}">S</figure-callout>}}_1}=\frac{P_2}{{\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="C0310804700173.png"\; state="\{\{state\}\}">S</figure-callout>}}_2}=\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;=\frac{P_n}{S_n}$

$\frac{Q_1}{{\mathrm{<figure-callout\; id="1"\; label="S"\; filenames="C0310804700162.png,C0310804700173.png"\; state="\{\{state\}\}">S</figure-callout>}}_1}=\frac{Q_2}{{\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="C0310804700173.png"\; state="\{\{state\}\}">S</figure-callout>}}_2}=\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;=\frac{Q_n}{S_n}$

In the formula: S ₁, S ₂Sn represents the rated capacity of inverter;

Before promptly should sending the active power value of reality output and reactive power value, they are changed relational expression according to mark handle by the power calculation unit of every inverter.

The present invention adopts the characteristics of output power of instantaneous reactive power theory and parellel inversion power, and promptly the frequency of the output voltage by changing inverter is controlled the active power of output; Control the reactive power of output by the output voltage amplitude that changes inverter, thereby can be similar to decoupling zero control to the frequency of inverter (phase place) and two key elements of amplitude by the active power P and the reactive power Q of output.Though there is interconnected holding wire in system, but signal that interconnected holding wire transmits is direct current, can suppress the interference in the process of long Distance Transmission comparatively easily, therefore principal and subordinate's control mode has higher utility at distributed generation system, ups system automatically, the current-sharing effect is fine, and electric voltage frequency, the amplitude stability of system are good.

Description of drawings

Fig. 1 is the equivalent circuit diagram of two inverters group net operation in parallel;

Fig. 2 is automatic principal and subordinate's control technology schematic diagram;

Fig. 3 selects the main control circuit schematic diagram automatically;

Fig. 4 is the automatic host-slave parallel operational system of inverter figure;

Fig. 5 is the automatic host-slave parallel control of a digital-analog mixed type inverter block diagram;

Fig. 6 is output voltage waveforms and the output current wave figure of separate unit high-performance inverter impact when subtracting bridge rectifier filtering load;

Unloaded circulation oscillogram when Fig. 7 is two inverters parallel connections;

The output current wave figure of two parellel inversion powers when Fig. 8 is the load of impact drag reduction;

The output current wave figure of two parellel inversion powers when Fig. 9 subtracts bridge rectifier filtering load for impact.

The present invention is described in further detail below in conjunction with embodiment that accompanying drawing and inventor provide.

Embodiment

Before introducing particular content of the present invention, at first introduce the characteristics of output power of inverter in parallel, afterwards labor automatic host-slave parallel networking control strategy and implementation thereof again.

1. inverter power output in parallel is analyzed

The distributed generation system or the ups system that compose in parallel by inverter, it is the system of a complexity, the alternating voltage of each inverter output can equivalence be a controllable voltage source, its frequency, phase place, amplitude be cooperation mutually, common burden load current promptly will be realized the balanced control of load current.For the ease of analyzing, below be that example is analyzed with two inverters group net operations in parallel.Equivalent circuit diagram when Fig. 1 is two inverters group net operations in parallel comprises two ideal inverse variable power source modules in parallel and is connected on load on the AC bus, wherein Z ₁, Z ₂Be line impedance, Z ₀Be load impedance.

In distributed generation system, the resistance of circuit is less, and line impedance mainly is perception, i.e. Z ₁≈ j ω L ₁, Z ₂≈ j ω L ₂, and the output voltage of inverter of two parallel operations among the hypothesis figure Be standard sine, and their capacity is respectively S ₁, S ₂, and S ₂=nS ₁, then:

The complex power of inverter 1 supply load is:

${\mathrm{<figure-callout\; id="1"\; label="S"\; filenames="C0310804700162.png,C0310804700173.png"\; state="\{\{state\}\}">S</figure-callout>}}_1=P_1+\mathrm{<figure-callout\; id="1"\; label="j\; Q"\; filenames="C0310804700162.png,C0310804700173.png"\; state="\{\{state\}\}">j</figure-callout>}{Q}_{}{}_1=U_0{\stackrel{\&CenterDot;}{I}}_1---\left(1\right)$

The output current of inverter 1 is:

Draw by formula (1), (2):

Because the output voltage of general inverter

With system voltage

Between phase difference very little, sin  then ₁≈  ₁If make U ₁=k ₁U ₀Then draw by formula (3):

In the formula $k_P$ $1_{}=\frac{K_1{U}_0^2}{\mathrm{\&omega;}{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="C0310804700162.png,C0310804700173.png"\; state="\{\{state\}\}">L</figure-callout>}}_1}$ Be the active power coefficient;

Be the reactive power coefficient;

$Q_{01}=\frac{U_0^2}{\mathrm{\&omega;}{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="C0310804700162.png,C0310804700173.png"\; state="\{\{state\}\}">L</figure-callout>}}_1}$

The power output that in like manner draws inverter 2 is:

Can draw the power characteristic of each inverter output in parallel according to formula (4), (5):

1) active power of inverter output depends primarily on phase angle , and proportional with phase difference, and phase difference surpasses the former and sends active power, otherwise absorbs active power; The big more active power of sending or absorbing of phase difference is big more.The adjusting of inverter phase angle  realizes by the fine setting frequency f, therefore, regulate the active power of each inverter output, only needs the frequency of output voltage is done corresponding the adjustment.

2) reactive power of inverter output then depends primarily on the voltage magnitude U of output, and the high person of amplitude sends reactive power, on the contrary absorbing reactive power; The output voltage amplitude difference is big more, send or the reactive power that absorbs big more.

The frequency of the output voltage by changing inverter control output active power, control the reactive power of output by the output voltage amplitude that changes inverter, thereby the approximate decoupling zero that the frequency of inverter (phase place) and two key elements of amplitude active power P and reactive power Q by output carries out non-strictness is controlled.This power characteristic that just is being based on the automatic host-slave parallel networking of the relevant inverter of the present invention synchronous operation control strategy and no interconnected holding wire independence control strategy realizes.

2. automatic host-slave parallel networking control strategy

2.1 automatic host-slave parallel control principle

Automatically principal and subordinate's control technology is a kind of parallel system of redundancy, it is based on, and the power characteristic of inverter output in parallel controls, that is: the active power of inverter output in parallel depends primarily on phase angle , and phase difference surpasses the former and sends active power, otherwise absorbs active power; The reactive power of parellel inversion power output then depends primarily on the voltage magnitude U of output, and the high person of amplitude sends reactive power, on the contrary absorbing reactive power.The adjusting of inverter phase angle  realizes by the fine setting frequency f, regulate the active power of each inverter output, only needs the frequency of output voltage is done corresponding the adjustment.The frequency of output voltage that therefore, can be by changing inverter is controlled the active power of output; Control the reactive power of output by the output voltage amplitude that changes inverter, thereby can be similar to decoupling zero control to the frequency of inverter (phase place) and two key elements of amplitude by the active power P and the reactive power Q of output.Inverter is when parallel running, and each power module can be according to capacity and the meritorious regulated quantity Δ P of output, the idle regulated quantity Δ Q of self, then to the given f of its frequency _r, the given U of voltage magnitude _rRegulate the inhibition with circulation of dividing equally that realizes load current accordingly.

Fig. 2 is the schematic diagram of automatic principal and subordinate's control technology.As can be seen from the figure, every inverter in parallel has oneself oscillator, voltage waveform controller, and active power is selected main control unit automatically, reactive power is selected main control unit automatically.System is by selecting the control of master unit automatically, automatically the big module of active power of output as meritorious primary module, all the other modules then for meritorious from module, active power bus P _BUSValue by the active power of output power decision of meritorious primary module; System is by selecting the control of master unit automatically, and exporting the big module of reactive power as idle primary module, all the other modules then are idle from module, reactive power bus Q automatically _BUSValue by the reactive power decision of idle primary module output, all desirable reactive powers from module output all should be Q _BUSValue.Therefore there are meritorious primary module and idle primary module in the system simultaneously.

If a certain inverter active power of output P _iAnd reactive power Q _iNot desirable P _BUSSum Q _BUSValue, then its deviation is:

$\left\{\begin{array}{c}\mathrm{\&Delta;}{P}_i=P_{\mathrm{BUS}}-P_i\\ \mathrm{\&Delta;}{Q}_i=Q_{\mathrm{BUS}}-Q_i\end{array}\right.---\left(6\right)$

The active power deviation and the reactive power deviation that can be drawn inverter i output by formula (4) are:

Therefore to make every inverter realize the consistent of power output and primary module, as long as every electric current I and output voltage V that inverter oneself is exported by sampling from module from module ₀Calculate the active power P of output _iAnd reactive power Q _i, and respectively with active power bus P _BUSWith reactive power bus Q _BUSRelatively, obtain deviation delta P _iWith Δ Q _i, again with Δ P _iAs phase place  _iCompensation rate, Δ Q _iAs amplitude U _iCompensation rate is adjusted the voltage of output, realizes each inverter load-sharing power in parallel, thereby has realized high-precision sharing control between inverter.

If the capacity of inverter in parallel does not wait in system, then to the active power and the reactive power of its output be marked the change processing according to the capacity of inverter, thereby make each inverter can bear the active power and the reactive power of load by its capacity, be the more power of inverter output capacious, the inverter output less power that capacity is little.Mark is changed relational expression:

$\frac{P_1}{{\mathrm{<figure-callout\; id="1"\; label="S"\; filenames="C0310804700162.png,C0310804700173.png"\; state="\{\{state\}\}">S</figure-callout>}}_1}=\frac{P_2}{{\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="C0310804700173.png"\; state="\{\{state\}\}">S</figure-callout>}}_2}=\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;=\frac{P_n}{S_n}---\left(8\right)$

$\frac{Q_1}{{\mathrm{<figure-callout\; id="1"\; label="S"\; filenames="C0310804700162.png,C0310804700173.png"\; state="\{\{state\}\}">S</figure-callout>}}_1}=\frac{Q_2}{{\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="C0310804700173.png"\; state="\{\{state\}\}">S</figure-callout>}}_2}=\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;=\frac{Q_n}{S_n}---\left(9\right)$

Before promptly should sending the active power value of reality output and reactive power value by the power calculation unit of every inverter, should be with they rated capacity S divided by inverter _iMark and change processing.

2.2 select the principle and the implementation thereof of main control unit automatically

Automatically selecting main control unit is a key link of automatic host-slave parallel controlling schemes, meritorious primary module and idle primary module that it determines system according to the active power and the reactive power of the output of each inverter module of parallel connection.The module that active power of output is big is designated as meritorious primary module, and meritorious primary module competition automatically obtains active power bus P _BUS, and the value of own active power of output outputed to active power bus P _BUSOn, gaining merit that other are all then abandoned active power bus P automatically from module _BUSCompetition, and active power bus P _BUSValue as the benchmark of own active power of output, promptly all meritorious from module according to P _BUSValue regulate oneself output active power; In like manner, the big module of output reactive power is designated as idle primary module, and idle primary module competition automatically obtains reactive power bus Q _BUS, and oneself output reactive power value output to reactive power bus Q _BUSOn, other all idlely then abandons automatically reactive power bus Q from module _BUSCompetition, and reactive power bus Q _BUSValue as the own benchmark of exporting reactive power, promptly all idle from module according to Q _BUSValue regulate oneself output reactive power.

Automatically select main control circuit, as shown in Figure 3.In the drawings, because the unilateral conduction of diode has only meritorious (idle) prominent module, just conducting of diode, the value of meritorious (idle) power generatrix equals meritorious (idle) performance number of meritorious (idle) the prominent module of output.Under normal circumstances, meritorious (idle) of each module output equates, if i ^#Meritorious (idle) power of module output increases suddenly, becomes one maximum in n the module, so, P _i(Q _i) rise, this module becomes meritorious (idle) primary module automatically, and other module is from module, at this moment, P _BUS=P _i(Q _BUS=Q _i), the Δ P of primary module _i=0 (Δ Q _i=0), and respectively from the P of module _k(Q _k) and P _BUS(Q _BUS) relatively, produce meritorious (idle) power error Δ P _k(Δ Q _k), error is adjusted the frequency (amplitude) of its output voltage thus, thereby realizes automatic load-sharing power.

Because the diode among Fig. 3 is included in the inside of voltage follower, therefore the power-sharing error that does not exist the forward voltage drop of diode to bring, does not exist the power-sharing error in theory.In the practical circuit, proportional control is all adopted in choosing master and power-sharing control automatically, and this makes the stability of a system good, the rapid dynamic response speed of power-sharing control.This another advantage of selecting main control circuit automatically is active power bus P _BUSWith reactive power bus Q _BUSBe low-impedance, to insensitive for noise.

According to above analysis, made the automatic master-slave control method of sinusoidal pulse width modulation inverter, system is as shown in Figure 4.In conjunction with Fig. 4, further specify the course of work of the automatic principal and subordinate's control of inverter.Suppose i ^#The active power of output P of inverter module _iGreater than all the other each modules, then active power bus P _BUSBy amplifier A _PiDrive, then P _BUS=P _i, i ^#The inverter module from module, draws for meritorious for meritorious primary module, all the other modules

Δ P _j=P _i-P _j＞0, (j ≠ i) wherein

So Δ f _j＞0,

Thereby f _j=f _Rj+ Δ f _j

Be j ^#The frequency of inverter module output voltage is in its given frequency f _RjThe basis on compensation Δ f _j, the frequency of its output voltage is improved, the phase place of output voltage moves forward, thereby makes j ^#The active power of output P of inverter module _jIncrease gradually; At P _jIn the process that increases, i ^#The frequency of inverter module remains unchanged, and its phase place is relative to moving backward, i.e. P _iReduce gradually.Finally, the active power of each inverter module output of parallel running is tending towards equal.In meritorious balanced adjustment process, the frequency of each inverter, the Synchronization Control of phase place have also been realized simultaneously.In like manner, can realize dividing equally of reactive power.

In the automatic host-slave parallel operation control procedure of inverter, there are meritorious primary module and idle primary module, the frequency of system is by the given reference frequency decision of meritorious primary module, the voltage magnitude of system is by output voltage (given reference voltage) decision of idle primary module, therefore the frequency and the voltage magnitude of system are stable, and it is very high that the frequency accuracy of system and amplitude precision can be done.Simultaneously, the consistency of the consistency of the active power of each inverter output and reactive power is all fine.

2.3 the realization circuit of automatic host-slave parallel networking controlling schemes

According to above analysis, the present invention proposes the automatic host-slave parallel controlling schemes of a kind of high performance digital-analog mixed type inverter, its control block diagram is as shown in Figure 5.It adopts high speed digital signal processor TMS320F240 and extends out voltage, electric current, the active power bus P that 12 A/D detect output _BUSAnd reactive power bus Q _BUSAnd based on instantaneous reactive power theory, calculate active power of output P, the reactive power Q of inverter, calculate frequency f and amplitude U then, synthetic more given voltage instruction, after deliver to the high-performance inverter after 12 D/A conversions, inverter will be according to given voltage instruction output sinusoidal voltage.

Realize dividing equally of active current and reactive current, reduce the circulation between the inverter, must improve the resolution of control resolution, the especially frequency of inverter frequency and amplitude.In the controlling schemes of the present invention, the frequency adjustment resolution of the voltage instruction that DSP sends is 200,000/, this is enough to guarantee the dividing equally of active power of inverter; It is four one thousandths that the amplitude of the voltage instruction that DSP sends is regulated resolution, is enough to guarantee that the reactive power of inverter divides equally, and makes the operation of system stability in parallel.

The high-performance inverter is as the actuator of voltage given instruction, and it has high stability, high voltage stability precision, the high sinusoidal degree of output.It adopts a kind of controlling schemes of novelty, and this scenario-frame is simple, two simple PI adjustable rings is only arranged: instantaneous voltage waveform outer shroud, high speed capacitive current inner ring.The instantaneous voltage outer shroud guarantees the tracking accuracy of output voltage, at a high speed, the capacitive current inner ring of low steady-state error can overcome because of the influence to output waveform of the fluctuation of load or disturbance voltage, make inverter realize that output voltage is near pure sinusoid, and the nonlinear load adaptive capacity is strong, harmonic wave of output voltage resultant distortion rate is little under the diode rectification loading condition, rapid dynamic response speed, adjustment process was short when the impact Reduction of Students' Study Load was carried, output voltage precision height.

Because the high-performance inverter adopts the voltage waveform control technology, in inverter parallel system, line impedance is indispensable, otherwise the voltage waveform ring of inverter can lose efficacy, and makes the inverter cisco unity malfunction.In the inverter parallel system of reality, the output of every inverter has sealed in a suitable resistance.Seal in line impedance and can make the voltage waveform of nonlinear load that certain distortion is arranged, but it can suppress the harmonic circulating current between parellel inversion power, make the distortion power of inverter load-sharing, and needn't consider dividing equally of distortion power from controlling.

2.4 the experimental result of automatic host-slave parallel control

The automatic host-slave parallel control method of digital-analog mixed type inverter that proposes according to the present invention; made the parallel system of two inverters; the major parameter of every inverter is as follows: capacity is 1.5kVA; switching frequency is 20kHz; unloaded output voltage is 110V; unloaded output voltage frequency is 50Hz, and the series circuit impedance is 0.2mH.Fig. 6～9 are relevant experimental waveform.

Fig. 6 is output voltage waveforms and the output current wave of separate unit high-performance inverter when impact subtracts bridge rectifier filtering load.As can be seen from Figure 6: when the high-performance inverter subtracts bridge rectifier filtering load at impact, output voltage waveforms remains unchanged (the output voltage effective value when actual measurement zero load and loading all is about 110V) substantially, and when the impact Reduction of Students' Study Load is carried, the dynamic adjustment process of output voltage very of short duration (the actual measurement adjusting time is 200 μ s), the harmonic wave resultant distortion rate (THD) that loads the back output voltage is 0.17%.

Unloaded circulation waveform when Fig. 7 is two inverters parallel connections, the effective value of the unloaded circulation of actual measurement is about 0.05A, only is 0.4% of output-current rating.

The output current wave of two parellel inversion powers when Fig. 8 is the load of impact drag reduction, the current peak of two inverter outputs is respectively 5.4A, 5.5A.

The output current wave of two parellel inversion powers when Fig. 9 subtracts bridge rectifier filtering load for impact, the electric current peak-to-peak value of two inverter outputs is respectively 33.8A and 32.2A.From Fig. 9,10 as can be seen, the load current effect of dividing equally is fine.

3. invention effect

In the automatic host-slave parallel operation control process of inversion power supply, the frequency of system is given by meritorious primary module Decide the benchmark frequency and determine that the voltage amplitude of system is by the output voltage (given benchmark voltage) of idle primary module Determine, so the frequency of system and voltage amplitude be stable that frequency accuracy and the amplitude precision of system can That does is very high; Simultaneously, because the power-sharing ring is outer shroud, can overcome the inversion power supply that is included in the ring All errors (comprise that each inversion power supply is because detecting, control frequency, phase place and the width of cloth of the output voltage that brings The error of value, and the fluctuation of the fluctuation of direct current bus, load etc.), thereby each inversion power supply output The uniformity of active power and the uniformity of reactive power are all fine, and the current-sharing effect between the inversion power supply is fine.

Automatic principal and subordinate controls the parallel connection of parallel system and controls the electric current that does not detect load, so load can be branch Cloth. Each of parallel running inversion power supply can be shared according to its capacity the active power, idle of load Power, and be not subjected to the impact of circuit impedance.

The networking control in parallel of system is what to finish under the control of automatically selecting the main control unit. Automatically select master control Built in there not being in theory the power-sharing error, and the ratio control is all adopted in the main and power-sharing control of choosing automatically System, this is so that system's stability is good, and the dynamic responding speed of power-sharing control is fast. This selects master control automatically Another advantage of circuit processed is active power bus P_BUSWith reactive power bus Q_BUSLow-impedance, right Noise is insensitive, no matter the power bus be open circuit or short circuit, do not affect the performance of each module.

Although there is active power bus P in the system_BUSWith reactive power bus Q_BUS, reduce to a certain extent The reliability of system, increased the cost of system, but compared with concentrating control, traditional principal and subordinate's control, The signal that these two buses are transmitted is the direct current signal substantially, and the pass band of signal line does not need too high, if Some filtering links of suitable increase are eliminated and are disturbed, and then these two buses can long distance be laid. And Concentrate in control, the principal and subordinate's control, the current command signal line between the inversion power module, at linear load What transmit in the situation is the interchange signal of a basic ripple frequency, in the situation of non-linear load, and this instruction letter The transmission of number line be a fundamental signal that comprises high-frequency harmonic, so the current command signal line is difficult for long distance Lay, otherwise signal is decayed, is disturbed seriously.

Automatically principal and subordinate's control is the system of a redundancy, every inversion power module status on physical arrangement Be equal to, during any inversion power supply (comprising primary module) fault, as long as it can withdraw from fast and be System does not just affect the normal operation of whole system, and the reliability of system is very high.

In sum, in the systems such as distributed generating, UPS, sinusoidal pulsewidth modulation inversion electricity of the present invention The automatic host-slave parallel control method in source has a good application prospect.

Claims (1)

1. the automatic host-slave parallel control method of sinusoidal pulse width modulation inverter is characterized in that this method may further comprise the steps at least:

With meritorious primary module and the idle primary module in the automatic principal and subordinate's control system of inverter, by selecting the control of master unit automatically, automatically the big module of active power of output as meritorious primary module, all the other modules then for meritorious from module, active power bus P _BUSValue by the active power of output decision of meritorious primary module; By selecting the control of master unit automatically, exporting the big module of reactive power as idle primary module, all the other modules then are idle from module, reactive power bus Q automatically _BUSValue by the reactive power decision of idle primary module output, all desirable reactive powers from module output all should be Q _BUSValue;

Every inverter is from electric current I and the output voltage V of module by sampling oneself output ₀Calculate the active power P of output _iAnd reactive power Q _i, and respectively with active power bus P _BUSWith reactive power bus Q _BUSRelatively, obtain active power deviation and reactive power deviation, again with the active power deviation as phase place  _iCompensation rate, reactive power deviation are as amplitude U _iCompensation rate is adjusted the voltage of output, realizes each inverter load-sharing power in parallel and the sharing control between inverter;

If the capacity of inverter in parallel does not wait in the system, then the active power and the reactive power of its output are handled according to following mark change relational expression according to the capacity of inverter:

$\frac{P_1}{S_1}=\frac{P_2}{S_2}=\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;=\frac{P_n}{S_n}$

$\frac{Q_1}{S_1}=\frac{Q_2}{S_2}=\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;=\frac{Q_n}{S_n}$

In the formula: S ₁, S ₂Sn represents the rated capacity of inverter, before promptly should being sent the active power value of reality output and reactive power value by the power calculation unit of every inverter, they is changed relational expression according to mark handle.

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